Method and assembly for preventing the production of windborne debris

ABSTRACT

A method and assembly for preventing the production of windborne debris from a surface of an object, particularly a roof surface, having roof gravel, under the influence of gale-force winds; and to a method of making the assembly. The method comprises locating a wind-permeable perforate sheet adjacent on or above the particulate material on the surface as to prevent the production of the flying debris.

FIELD OF THE INVENTION

This invention relates to a method and assembly for preventing the production of windborne debris from a surface of an object, particularly a roof surface, having roof gravel, under the influence of gale-force winds; and to a method of making said assembly.

BACKGROUND TO THE INVENTION

Reference is made to the seminal article by Minor, Joseph E., Journal of Wind Engineering and Industrial Aerodynamics, 53, (1994), 207-227, entitled “Windborne Debris and the Building Envelope”, for the damaging effects of windborne debris, particularly, roof gravel, in gale-force winds, particularly hurricanes.

The above reference reported field surveys of typical built-up roofs having conventional “tar and gravel” surfaces that established the average roof gravel size to be 0.6 g., and an average large size to be 5 g.

While the problem of addressing the damaging effects of flying debris, including roof gravel, on buildings and mobile houses, has been described in the literature and, to some degree, the solution commercialized, the intended solution is to utilize netting located adjacent, around or over the building or mobile home to prevent or alleviate the damage from the debris already in motion created under the influence of the strong wind. Examples of publications, include U.S. Pat. No. 5,579,794—Sporta, Joseph, Dec. 3, 1996; U.S. Pat. No. 6,176,050, Gower, Ted, Jan. 23, 2001; and U.S. Pat. No. 6,412,540, Hendee, Charles C., Jul. 2, 2002.

However, the concept and means of preventing damage to the aforesaid structures from debris under the influence of strong winds by preventing the production of damaging flying debris has not been, heretobefore, described.

SUMMARY OF THE INVENTION

It is an object of the present invention to provide a method of preventing the production of damaging flying debris, particularly, roof gravel.

It is a further object of the present invention to provide an assembly of use in the aforesaid method.

It is a yet further object to provide a method of making said assembly.

Accordingly, in one aspect, the invention provides a method for preventing the production of flying debris comprising particulate material from a surface of a structure having said particular material under the influence of gale-force winds, said method comprising locating a wind permeable perforate sheet adjacent on or above said particulate material on said surface as to prevent the production of said flying debris.

The structure is, preferably, but not limited to, a residence, industrial or commercial building having a roof surface that is, preferably, in part, flat and comprises a “tar and gravel” finish.

The roof surface is of particular value when the gravel has an average weight selected from 0.5 g. to 5 g.

The perforate sheet of use in the practice of the invention is, preferably, but not limited to, a mesh, netting and the like, most preferably a flexible, webbed netting of the form and material as described in aforesaid U.S. Pat. No. 5,579,794.

The sheet has perforations of such dimensions as to operably prevent passage, therethrough, of significant amounts of the particulate material.

Although the perforate sheet may rest adjacent upon the tar and gravel surface, preferably, it is located adjacent and at a distance above the surface as to not hinder or interfere with rain water run-off from the roof.

Further, preferably, the perforated sheet is so located as to allow the sheet and the roof surface to be traversed, i.e. walked upon by a person, such as a person who requires access to the edges of the flat roof to permit the erection of window, stone, brick and the like, washing equipment and the resultant washing action therewith; and to maintenance workers for servicing roof top equipment such as air conditioners, chimneys and pumps, without damage to the sheet or roof.

In a further aspect, the invention provides an assembly comprising

-   -   (a) an object having an upper surface;     -   (b) perforate sheet means located adjacent on or above said         upper surface;     -   (c) perforate sheet attachment means for securing said perforate         sheet adjacent on or above said upper surface and attached to         said perforate sheet means at least along a periphery thereof         and for securing said perforate sheet means to said object;     -   (d) particulate material on said surface and below said         perforate sheet; and wherein said perforate sheet having         perforations of such dimensions as to operably prevent passage,         therethrough, of said particulate material under the influence         of gale force winds.

Attachment means may comprise, for example, roof anchors, lag shield anchors, concrete wedge anchors, sleeve anchors, expansion bolts, anchors, screws, including lag eye bolt screws, and the like, which may be permanent fixtures or attachably installed and detachably removed when desired.

Although not preferred, the attachment means in this specification and claims may comprise suitable, relatively heavy objects, such as sandbags, concrete blocks, iron members and the like, resting on and bringing portions of the sheet into contact with the roof surface.

In a further aspect, the invention provides a method of providing an enlarged bonded perforate sheet from at least two non-bonded sheets, said method comprising ultrasonic bonding of the non-bonded sheets, one sheet to the other.

Preferably, each of the perforate sheets is a netting, mesh or like structure.

Ultrasonic plastic welding assembly is the joining or reforming of thermoplastic materials through the use of heat generated from high-frequency mechanical motion. It is accomplished by converting high-frequency electrical energy into high-frequency mechanical motion. That mechanical motion, along with applied force, creates frictional heat at the plastic material's mating surfaces (joint area) so that the plastics material melts and forms a molecular bond between the parts.

The method is of particular value when relatively large areas of perforate sheets are desired, particularly, but not limited, to use for preventing the production of windborne debris in the method, as hereinabove defined. The aforesaid ultrasonic bonding method is also of value when relatively smaller areas of perforate sheets are desired for use around rooftop articles protruding above the roof surface.

The ultrasonic bonding method of use in the present invention negates the need for the production of desired areas and shapes of perforate sheets off-site from the installation location and, thus, dispense with the need to transport large and heavy amounts from any off-site production center, with its attendant inconvenience and/or difficulties.

Surprisingly, I have discovered that the aforesaid ultrasonic bonding process of perforate sheets, i.e. sheets not being aperture-free, particularly, the aforesaid preferred netting, mesh and like forms, provides satisfactorily strong bonds between adjacent sheets of use in the present invention.

Small hand held ultrasonic welders can be used to bond together any cutting of the netting sections that needs to be done to facilitate any cut-aways. Some brand name manufacturers of ultrasonic welders are Duane, Lester, Branson, and Mecasonic.

Accordingly, the invention provides an enlarged perforated sheet comprising at least two original sheets when bonded in a process as hereinabove defined.

In a further aspect, the invention provides an assembly as hereinabove defined comprising at least two perforate sheets ultrasonically bonded one to another as hereinabove defined.

In preferred embodiments, the perforate sheet is formed of a thermoplastic material further comprising a UV stabilizer. The sheet is, preferably, resistant to biological and chemical degradation and, most preferably, sufficiently flexible to allow vertical and sideways movement under the weight of a person without being damaged or causing the person to fall or have difficulty walking thereon.

The assembly, according to the invention, may be assembled for permanent installation or only installed prior to an expected need, say, in the event of a hurricane.

The perforate sheet is preferably formed of a flexible, woven synthetic material. The material may be inherently resistant to the natural elements or coated with materials so resistant. An example of an uncoated material is a polypropylene and a suitably coated material is a vinyl coated polyester.

It will be readily appreciated that the perforate sheet need not be so impact resistant as that described in the aforesaid prior art patents which are contacted by windborne debris having very significant velocities and momentums, because the particulate material in the present invention has limited opportunity to gain such damaging momentum and is restrained and trapped under the perforate sheet.

BRIEF DESCRIPTION OF THE DRAWINGS

In order that the invention may be better understood, a preferred embodiment will now be described by way of example only, wherein

FIG. 1 is a diagrammatic plan view of an assembly, according to the present invention;

FIG. 1A is a diagrammatic enlarged view of a portion of FIG. 1 showing an exaggerated mesh size;

FIG. 2 is a diagrammatic side sectional view, in part, of an assembly according to the invention; and wherein the same numerals denote like parts.

DETAILED DESCRIPTION OF A PREFERRED EMBODIMENT

With reference to FIG. 1, this shows, generally, as 10, a BIG-BOX retail store, having a flat roof 12 with a roof periphery 14 and having a “tar and gravel” surface 16. Upon roof 12 is a plurality of typical roof articles, namely, air conditioner unit 18, air vents 20, window cleaning equipment supports 22, and rain water run-off apertures 24 for water down-pipes (not shown).

With reference also to FIG. 1A and FIG. 2, located between aforesaid roof articles 18, 20, 22 and 24 and roof periphery 14 adjacent and 2-3 cm above surface 16 is a flexible, webbed netting 26, formed of a water resistant braided polyethylene. Netting 26 is attached to roof 12 and roof periphery 14 and by attachment bolts 28 and to a middle portion 30 by screw bolts 32. Netting 26 is at a distance of about 2 cm. above surface 16. Between netting 26 and surface 16 is loose particulate, B3 roof gravel 34, airborne by turbulent wind forces 36.

FIG. 1A shows netting 26 comprising two smaller portions 26A and 26B bonded at strip 36 by ultrasonic bonding “on-site” (in situ) assembled while on roof 12.

Although this disclosure has described and illustrated certain preferred embodiments of the invention, it is to be understood that the invention is not restricted to those particular embodiments. Rather, the invention includes all embodiments which are functional or mechanical equivalents of the specific embodiments and features that have been described and illustrated. 

1. A method for preventing the production of flying debris comprising particulate material from a surface of a structure having said particular material under the influence of gale-force winds, said method comprising locating a wind permeable perforate sheet adjacent on or above said particulate material on said surface as to prevent the production of said flying debris.
 2. A method as claimed in claim 1 wherein said surface comprises a roof surface of a building.
 3. A method as claimed in claim 2 wherein said roof surface comprises at least a portion that is substantially flat.
 4. A method as claimed in claim 1 wherein said particulate material comprises roof gravel.
 5. A method as claimed in claim 4 wherein said roof gravel has an average weight selected from 0.5 g. to 5 g.
 6. A method as claimed in claim 1 wherein said perforate sheet comprises netting.
 7. A method as claimed in claim 5 wherein said netting is flexible, webbed netting.
 8. A method as claimed in claim 1 wherein said perforate sheet is located adjacent at a distance above said surface as to not hinder or interfere with water run-off from said roof.
 9. A method as claimed in claim 1 wherein said perforate sheet is located adjacent at a distance above said surface as to allow said perforate sheet and said surface to be traversed by a person without damage to said perforate sheet.
 10. An assembly comprising (a) an object having an upper surface; (b) perforate sheet means located on or adjacent above said upper surface; (c) perforate sheet attachment means for securing said perforate sheet adjacent on or above said upper surface and attached to said perforate sheet means at least along a periphery thereof and for securing said perforate sheet means to said object and (d) particulate material on said surface and below said perforate sheet and wherein said perforate sheet having perforations of such dimensions as to operably prevent passage, therethrough, of said particulate material under the influence of gale force winds.
 11. An assembly as claimed in claim 10 wherein said object is a roof of a building.
 12. An assembly as claimed in claim 11 wherein said roof comprises a surface that is essentially flat.
 13. An assembly as claimed in claim 10 wherein said particulate material comprises roof gravel.
 14. An assembly as claimed in claim 13 wherein said roof gravel has an average weight selected from 0.5 g. to 5 g.
 15. An assembly as claimed in claim 11 wherein said perforate sheet comprises netting.
 16. An assembly as claimed in claim 15 wherein said netting is flexible webbed netting.
 17. An assembly as claimed in claim 11 wherein said perforate sheet is located adjacent at a distance above said surface as to not hinder or interfere with water run-off from said roof.
 18. An assembly as claimed in claim 11 wherein said perforate sheet is located on or at a distance above said surface as to allow said perforate sheet to be traversed by a person without damage to said perforate sheet.
 19. A method of joining at least two perforate sheets, one to another to produce an enlarged perforate sheet, said method comprising ultrasound bonding with at least two sheets one to another.
 20. A method as claimed in claim 19 wherein said perforate sheet is netting or in the form of a mesh.
 21. An enlarged perforate sheet comprising at least two perforate sheets ultrasonically bonded one sheet to another sheet.
 22. An enlarged perforate sheet as claimed in claim 21 in the form of a netting or mesh.
 23. An assembly as claimed in claim 10 wherein said perforate sheet means comprises an enlarged perforate sheet comprising at least two perforate sheets ultrasonically bonded one sheet to another sheet.
 24. An assembly as claimed in claim 23 wherein said enlarged perforate sheet is in the form of a netting. 